.popup {
    position: fixed;
    top: 0;
    width: 100%;
    height: 100%;
    justify-content: center;
    align-items: center;    
    background-color: rgba(0, 0, 0, .5);    
    display: flex;

    visibility: hidden;
    opacity: 0;
    transition: visibility 0s .2s, opacity .2s;
}

